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(No Model.)

H. E. WAITE.

TRANSMITTER FOR TELEPHONES. No. 250,307. Patented Nov. 29,1881.

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Un'rrnn STATES Aren't Creme,

HENRY E. WAITE, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO CHARLES F. LIVERMORE, OF NEW YORK, N. Y.

TRANSMITTER FOR TELEPHONES.

SPECIFICATION forming part of Letters Patent No. 250,307, dated November 29, 1881. Application filed May 28, 1881. (No model.)

To all whom it may concern Be it known that I, HENRY E. WAITE, of Bridgeport, county of Fairfield, State of Connecticut, have invented new and useful Improvements in Transmitters for Telephones, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specitication, in which Figure 1 represents a vertical section through my improved transmitter. Fig. 2 is a horizontal section, showing an arrangement of a series of transmitters, looking from underneath. Fig. 3 is an end view of one form of my improved microphone detached, and Fig. 4 shows a modification in the construction of the same. My invention relates to a novel construction of the microphone, one or more of the carbon plates or conductors being made cylindrical in form, and resting within a cylindrical perforation in another piece or cylinder of carbon or equivalentconductingmaterial; tothearrangementof several cylinders of carbon or its equivalent, one within the other, thereby securing a number of contacts, or what I term a multiple contact, and to the employment ofanuniher or series of these microphones or multiple contacts within a single transmitter, each connected with a separate battery, and constitut- 0 ing a separate and independent microphone or transmitter, but all combining on the line and operating together to form a single transmitter.

In the accompanying drawings, A represents 5 the body or shell of the transmitter, made, by preference, in form approximating a hollow sphere cut away or flattened upon its lower side where it is secured to a base, stand, or other suitable support, B. About in the plane of the center of the bodyA is a diaphragm, O,

which, for the purpose of permitting the atmospheric sound-waves to pass it readily, and also for making it lighter, may be cut away at c 0 between its points of attachment to the 5 cylinder, as shown. This diaphragm may be of metal, cast in one piece with the body or shell A, or it may be made of cork, wood, or any other suitable material placed within and secured to the shell A, in which latter case, for convenience in inserting and securing the diaphragm, the shell, which may also be of wood or other suitable material, where made spherical in form, may be made in sections properly secured together after the diaphragm has been secured in place; but the shell may be made in the form of a hollow cylinder, and the diaphragm secured therein midway of its length, after which the cylinder may be closed by a suitable cap or cover.

To the lower face of the diaphragm C is secured the microphone,consistin g of a perforated block or cylinder, D, of carbon or other suitable conducting material, within which is placed a second block, D, of similar material, also cylindrical in form, and of an external diameter sufficienttocauseit justtolooselyfillthe borein the block D and give it a surface contact with said block or outer cylinder upon its entire periphery resting within the same. By this arrangement a greatly-increased surface contact is ob- 7o tained over what can be otherwise obtained from the same amount of carbon in different form and with great improvement in the results. I have found it of service, also, to increase the number of these inner cylinders to two, three, or more, as shown in the end View, Fig.3, where three hollow cylinders are shown arranged one within another, and'within the inner one a solid cylinder or rod, thus forming what I term a multiple contact, the inner one and the outer one being connected, one with the battery and thence with the ground, and the other with the line-wire, as shown.

In Fig. 4 another modification is shown, the microphone in this case consisting of two perforated blocks separated on the diaphragm C, with an inner cylinder, D, having its ends resting in and connecting said blocks, thus producing a multiple contact. In this case the outer blocks are connected, one with the bato tery and ground, and the other with the line.

In Figs. 1 and '2 a number of these micro phones are shown grouped upon the diaphragm C; but each, as will be seen,is connected with its own battery, and operates as a perfect trans- 9 5 mitter independent of the others, but the linewires are shown leading to and connecting with a single line, thereby combining the several microphones upon said line into a single complex transmitter and increasing its power; we

but it will be apparent that they may be connected with independent lines, and thus made to communicate the same message to different points and to different auditors.

The multiple contact or number of contacts referred to have been found to improve the action of the microphone, and to adapt it to long -1ines or distances, the number of sleeves or cylinders of carbon to be increased as the distance to be traversed by the message is increased.

Having now described my invention, I claim- 1. In a telephone-tramsmitter, a microphone consisting of a perforated block or cylinder of carbon or equivalent conducting material and a cylindrical piece or block of similar material resting within said perforated block or cylinder, substantially as described.

2. A microphone composed of two or more 20 cylinders of unequal diameters placed onewithin another, substantially as described.

3. The combination of two or more separate microphones having multiple contacts with the central equatorial diaphragm and the hollow 2 spherical resonant case to which the mouthpiece is applied, substantially as described.

In testimony whereof I have hereunto set my hand this 19th day of May, A. D. 1881.

HENRY E. WAITE.

Witnesses:

ALEX. MAHON, J. M. YZNAGA. 

